Method of Rotating a Welding Torch During Operation

ABSTRACT

A method of operating a welding torch using a rotating coupler assembly that operates between 0 and 800 amps. The rotating coupler assembly allows for 360 degrees of rotation while keeping rotational friction at a minimum. The breakaway torque for the rotating coupler assembly is insignificant and the rotating coupler assembly can be rotated with little effort by hand. While the rotating coupler assembly minimizes rotational friction the design allow for rotating coupler assembly to continue to operate after 1-5 mm of wear on the contact surfaces. An embodiment of the rotating coupler assembly can be quickly disconnected from the unicable.

RELATED APPLICATIONS

This application claims the benefit of the filing date of U.S. Utilitypatent application Ser. No. 15/813,932, filed on Nov. 15, 2017, entitled“Reduced Friction Rotating Coupler Assembly and quick disconnect for usewith Welding devises” by Juan Solis, the entirety of which isincorporated herein by reference.

BACKGROUND OF THE INVENTION A. Field of Invention

The present invention is in the technical field of Welding devices. Moreparticularly, the present invention is in the technical field of gasmetal arc welding (GMAW) and metal inert gas (MIG) welding torches.

B. Description of Related Art

Prior art welding torches used in welding metallic materials together,such as MIG welding torches, have generally utilized a fixed or rotatingconductor tube or goose neck mechanically and electrically connected toa unicable which generally supplies power, welding or shielding gas, andfiller wire to the MIG torch. The unicable generally comprises a coretube for passage of the filler wire, welding/shielding gas, and liner,copper cabling for conducting the electrical current to the torch, andshielded lead wires for controlling the operation of the torch. Theunicable is permanently attached to an end of a typical MIG torch,generally via a crimp or other permanent mechanical attachment. In MIGtorches with a fixed goose neck the unicable will undergo bending andflexing as the MIG torch is moved and rotated. This bending and flexingcyclically stresses the unicable and after a finite number of cycles theunicable will fail. In human operated torches the time needed to reachthe cycle life of an unicable is variable depending on the method of useby the operator. In robot operated torches the life a welding torchgenerally tends to be longer than a human operated torch due to thereduced range of movement experienced by the unicable in typical roboticwelding applications. The service life of a MIG unicalble used in arobotic application can be extended by the use of a MIG torch that isrotatable versus a fixed torch, resulting in increased productivity dueto the increase in the amount of time before the unicable requiresreplacement or service and the reduced movement required to performcertain operations. Rotating torches that can rotate a full 360 degreesor any amount less than 360 degrees, fully rotatable welding torches aremore desirable than rotatable welding torches that are limited to ˜270degrees or less. Prior attempts at a rotating welding torch have usedvarious methods to accomplish rotation. Such as U.S. Pat. No. 7,665,996by Jaeger et al. (hereinafter Jaeger) which uses a rotating powerconnector on the goose neck mating end of the unicable.

As seen in FIG. 2 of Jaeger, this design uses a connector pin 34 androtating stud 40 that are in direct contact with each other inside therotating power connector assembly. The rotating stud 40 has a bearing 62at approximately half the axial length of the rotating stud 40 tofacilitate rotation. The Jaeger design relies on multiple current pathsto ensure an electrical connection between the unicable and the gooseneck and uses a secondary contact ring 52 to accomplish this task. Thesecondary contact ring 52 of Jaeger is designed to act as a wedgebetween the rotating stud 40 and the inner housing 50. The electricalcontact faces of the rotating stud 40 and connector pin 34 arehorizontal faces that are pressed against one another by a spring(biasing member 58) that also pushes or wedges the contact ring 52between the tapered surface 60 of the inner housing 50 and contactportions 54 of the contact ring 52. This wedging produces frictionbetween the contact ring 52 and rotating stud 40 that increases theamount of torque required to turn the connector pin 34 about therotating stud 40. As result, the amount of breakaway torque required tospin the connector pin 34 is ˜0.32624 N-m (2.89 inch-lbs), which is asignificant amount if attempted by hand. The frictional force betweenthe connector pin 34 and rotating stud 40 causes mechanical wear on thecontact surfaces of the Jaeger invention which will eventually lead tothe failure of the welding torch in accordance with Jaeger. As can beseen in FIG. 4 of Jaeger, the invention of Jaeger is permanentlyattached to the unicable 18 via an unlabeled mechanical crimp seen belowthe location of the label “18” near the proximal end of the figure.

Another side effect of the significant breakaway torque required byJaeger and other prior art rotatable welding torches is the torsion andor minor rotation of the unicable at the mechanical attachment to theprior art torch. This results in visually observable movement, of theunicable relative to the robot arm, at the mechanical attachment to theprior art welding torch. The movement is not as significant as themovement that occurs in fixed head welding torches but does result inreduced service life of the unicable.

Typical power supplies for MIG welding torches can output between 0 and800 amps. The unicable and all portions of the MIG welding torch thatare part of the electrical circuit between the power supply and MIGwelding torch are required to withstand the maximum current output ofthe power supply being used for any given application.

SUMMARY OF THE INVENTION

The present invention provides a rotating power connector that reducesthe amount of torque required to spin the welding torch assembly about acentral axis. The present invention reduces the amount of torquerequired to spin the rotating assembly by reducing the amount of axialforce required to keep the rotating and contact elements of the assemblyin electrical communication. The reduction in axial force is partiallyaccomplished by using mating conical geometries (interlocking convex andconcave surfaces) that use the cone angle of the mating surfaces toreduce the axial component of the contact force need to maintainelectrical communication between the surfaces when compared to rotatingconnectors used in previous designs of rotating MIG Torches.Additionally the conical shape of the contact surfaces allows forincreased surface area versus designs that use horizontal faces that arein contact in the axial direction, such as the invention of Jaeger.Additionally, the present invention allows for embodiments that can bequickly disconnected from the unicable while allowing for rotation ofthe goose neck and wear in the axial direction by the internalcomponents of the rotating coupler assembly.

BRIEF DESCRIPTION OF THE DRAWINGS

Figures are not drawn to scale. The figures depict one or moreembodiment of the present invention, additional embodiments are notillustrated.

FIG. 1 is a cross section of a welding torch assembly including anembodiment of the present invention;

FIG. 2 is a partial cross section detailing an embodiment of the presentinvention;

FIG. 3 is a cross section of the constant pressure apparatus used by oneembodiment of the present invention;

FIG. 4 is a cross section of a rotating member used by one embodiment ofthe present invention;

FIG. 5 is a cross section of a second embodiment of the presentinvention that includes a quick disconnect from the unicable.

FIGS. 6a and 6b are cross sections of the receiving member and the maleand female connections of the quick disconnect used by the secondembodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the drawings, wherein like reference numerals designateidentical or corresponding parts throughout the several views,embodiments of the invention shown. The present invention is a reducedfriction rotating coupler assembly with or without quick disconnect fromthe unicable for use with welding torches.

A cross sectional view of an embodiment of the present invention can beseen in FIG. 1. The reduced friction rotating coupler assembly(hereinafter RCA) 1 is located inside the welding torch assembly 2. Thewelding torch assembly 2 is mechanically attached to a robotic arm (notshown) via a flanged interface 3 located at the proximal end of thewelding torch assembly 2. The welding torch assembly 2 is rotated abouta central axis 4 as the flanged interface 3 is rotated by the movementof the robotic arm (not shown).

As seen in FIGS. 1 and 2, the RCA 1 has an outer housing 5 that servesas an insulator and a means for positioning the RCA 1 via a interfacebetween the proximal end of the RCA 1 and the proximal end of the mainbody 7 of the welding torch assembly 2. A flange 6, located at theproximal end of the substantially cylindrical outer housing 5 of the RCA1 is positioned in a stepped recess located at the proximal end of themain body 7 of the welding torch assembly 2. The flange 6 limits theradial movement of the proximal end of the RCA 1 inside the weldingtorch assembly 2. The flange 6 is in mechanical communication with themain body 7 of the welding torch assembly 2 but not electricalcommunication due to the insulating properties of the outer housing 5 ofthe RCA 1.

As seen in FIG. 2, the substantially cylindrical inner housing 8 ispositioned within the outer housing 5 of the RCA 1 and extends forsubstantially the entire length of the RCA 1. A substantiallycylindrical rotating member 9 is positioned at the distal end of the RCA1 along the central axis 4 within the inner housing 8 of the RCA 1. Therotating member 9 is mechanically supported by at least one bearing 10.The bearing(s) 10 are in mechanical communication with the inner housing8 and rotating member 9. The bearing(s) 10 are centered within the innerhousing 8 and in turn center the rotating member 9 along the centralaxis 4. The material selection for the bearing(s) 10 does not require amaterial that is electrically conductive, materials with low electricalconductivity or insulating qualities (i.e. ceramic bearings) arepreferable as electrical conduction through the bearing(s) 10 wouldreduce the life of bearing(s) 10 by drying out the lubricant sealedwithin.

As seen in FIG. 2, the rotating member 9 has a first locking feature atthe proximal end of the rotating member 9, in this embodiment a flange11, is in mechanical communication with a bearing 10 thereby limitingthe axial movement along the central axis 4 of the rotating member 9within the RCA 1. The rotating member 9 has a second locking feature atthe distal end of the rotating member 9, in this embodiment a threadedlock ring 12. Threads 13 on the outer diameter of the distal end of therotating member 9 are in mechanical communication with the threaded lockring 12. When installed the lock ring 12 and the flange 11 limit theaxial movement of the rotating member 9 within the RCA 1.

As seen in FIG. 1-2, a constant pressure apparatus 14 is installed inthe proximal end of the RCA 1 within the inner housing 8 of the RCA 1.As seen in FIG. 3, the constant pressure apparatus 14 comprises areceiving member 15 and a sliding member 16. The receiving member 15 hasthreads 17 at the distal end of the receiving member 15 which engage thethreaded proximal end of the inner housing 8. A flange 18 of thereceiving member 15 engages the step 19 at the proximal end of the innerhousing 8 of the RCA 1, thereby setting the axial location the receivingmember 15 along the central axis 4. As seen in FIG. 1-2, the innerdiameter of sliding member 16 of the constant pressure apparatus 14 isin mechanical communication with the outer diameter of centering feature20 of the rotating member 9 via a centering feature 22, in thisembodiment an o-ring, of the sliding member 16 located at the distal endof the sliding member 16. The centering feature 22, in this embodimentan o-ring, centers the proximal end of the rotating member 9 along thecentral axis 4 as well as acting as a pneumatic seal. The centeringfeature 20 of the rotating member 9 is designed to allow for the slidingmember 16 to move towards to the distal end of the RCA 1 as the concavecontact surface 23 of the sliding member 16 wears into convex contactsurface 24 of the rotating member 9.

FIG. 1 shows the rotating member 9 and the sliding member 16 are inelectrical communication via a radial contact interface. In thisembodiment radial contact interface comprises a concave contact surface23 on the distal end of the sliding member 16 and a convex contactsurface 24 on the proximal end of the rotating member 9 of the RCA 1.The concave contact surface 23 and convex contact surface 24 are inmechanical and electrical communication with each other due to the forceexerted by an axial force member 25. In this embodiment the axial forcemember 25 is located in a recess in the proximal end of the slidingmember 16. When the receiving member 15 is seated in the step 19 locatedat the proximal end of the inner housing 8 of the RCA 1 the axial forcemember 25, in this embodiment a spring, exerts an axial force againstthe receiving member 15 and sliding member 16; as the receiving member's15 axial location is fixed by the flange 18 and step 19 of the innerhousing 8, the concave contact surface 23 of the sliding member 16 ispressed against the convex contact surface 24 of the rotating member 9thereby creating an electrical conduction path between the slidingmember 16 and the rotating member 9. The sliding member 16 and receivingmember 15 are designed to prevent rotation by the sliding member 16, inthis embodiment an anti rotation pin 29 is pressed into the receivingmember 15 and slip fit into the sliding member 16.

In some embodiments, an electrically conductive lubricant can be used toreduce friction between the contact surfaces of the sliding member 16and rotating member 9, including but not limited to oil or greasecontaining copper, silver, nickel, or other metal based or impregnatedlubricant. The sliding member 16, rotating member 9 and axial forcemember 25 are designed to allow between 1-5 mm of wear between thecontact surfaces before electrical conduction between the sliding member16 and rotating member 9 can no longer be maintained. The axial forcemember 25, in this embodiment a spring, exerts an axial force between44.48-111.20 N (10-25 lbf) on the sliding member 16 and the receivingmember 15. In one embodiment the initial spring load is 20 lbs, at thisspring load the breakaway torque of the RCA 1 is measured to be ˜0.202N-m (1.79 ft-lbs). The low breakaway torque required by the RCA 1 hasthe added benefit of allowing a welding torch in accordance with thepresent invention to rotate about a central axis 4 with zero tovirtually no torsion or rotation translated to the unicable. While inoperation, the unicable in a welding torch in accordance with thepresent invention will not be subjected to torsion loading or rotate asa result of rotation of the welding torch about the central axis 4.

The inner diameter of the receiving member 15 is designed to accommodateat least one compressible electric contact member, in this embodiment acanted coil spring. The compressible contact member(s) (not shown) areseated in radial grooves 26 in the receiving member 15 and conductelectricity between the sliding member 16 and the receiving member 15while allowing the sliding member 16 to move in the axial direction,along the central axis 4, while maintaining electrical conductionbetween the sliding member 16 and the receiving member 15.

The rotating member 9, sliding member 16, compressible contact member(s)(not shown), and receiving member 15 are manufactured out ofelectrically conductive materials (including but not limited to copper,brass, silver, and gold) and are in electrical communication. The innerhousing 8 and lock ring 12 can be manufactured from the same material asthe receiving member 15, sliding member 16, and or the rotating member 9but do not need to be manufactured from electrically conductivematerials as no secondary conduction path is needed by the presentinvention.

In one embodiment of the present invention the proximal end of thereceiving member 15 is configured as a hose barb 27 that extends beyondthe proximal end of the RCA 1 in the proximal direction about thecentral axis 4 and extends beyond the proximal end of the welding torchassembly 2 in the proximal direction about the central axis 4. The hosebarb 27 is mechanically connected to the core tube of an unicable (notshown). The hose barb 27 is crimped to the copper cabling of theunicable (not shown) creating a permanent mechanical and electricalconnection between the receiving member 15 and the unicable.

FIG. 5 shows another embodiment of the present invention. In thisembodiment the proximal end of this embodiment's receiving member 40 isconfigured as quick disconnect 30. As seen in FIGS. 6a and 6b , thequick disconnect 30 comprises a female connection 31 and male connection32. The proximal end of the male connection 32 is a hose barb 37 that isin mechanical and electrical communication with a unicable (not shown).The female connection 31 is designed to accommodate at least onecompressible electric contact member (not shown), in this embodiment acanted coil spring. The female connection 31 has at least one radialgroove 36 to accommodate a compressible electric contact member (notshown). The compressible electric contact member (not shown) conductselectricity between the female connection 31 and the male connection 32without the use of a permanent mechanical connection, such as a crimp.The quick disconnect 30 functions in a similar fashion as the radialgroove(s) 26 and compressible electric contact member(s) function as aslidable assembly in the RCA 1; the quick disconnect 30 allows for themale connection 32 to be inserted into the female connection 31 whileallowing for the conduction of 0-800 amps of electric current. Thisembodiment of the present invention has the advantage of being capableof disconnection from the unicable in a quick and repeatable fashion. Asa result, this embodiment also has the advantage of allowing the entirewelding torch assembly 2 to be removed from the robotic arm (not shown)without having to remove the unicable (not shown) from robotic arm (notshown). A significant saving in time and labor are achieved by thisembodiment because welding torch assembly 2 can be removed formaintenance without removal of the unicable, liner and filler materialrequired for normal operation of a welding torch.

The female connection 31, male connection 32, and compressible contactmember(s) are manufactured out of electrically conductive materials(including but not limited to copper, brass, silver, and gold) and arein electrical communication with each other and the RCA 1.

The quick disconnect 30 can include an anti-rotation feature, such as ananti-rotation pin 29 seen in the RCA 1. The quick disconnect 30 caninclude a releasable locking feature to prevent the removal of the maleconnection 32, in the axial direction along the central axis 4, after ithas been inserted into the female connection 31 without the lockingfeature being released.

1. A method of rotating an electric welding torch, the methodcomprising: providing a rotating coupler assembly comprising: a centralaxis that extends from a distal to a proximal end of the rotatingcoupler assembly; a rotating contact member axially disposed within therotating coupler assembly; a sliding contact member axially disposedwithin the rotating coupler assembly; a receiving member axiallydisposed within the rotating coupler assembly; at least one radialcontact member in mechanical and electrical communication with thesliding contact member and the receiving member; wherein the rotatingcontact member has a contact surface that is in mechanical andelectrical communication with a contact surface on the sliding contactmember.
 2. The method of claim 1, wherein said rotating contact member,sliding contact member and receiving member are axially installed withinan inner housing of the rotating coupler assembly.
 3. The method ofclaim 2, wherein said inner housing is axially installed within an outerhousing of the rotating coupler assembly.
 3. The method of claim 1,wherein said sliding contact member and rotating contact member are keptin mechanical and electrical communication via an axial member whichallows for at least 5 mm of wear between the contact surfaces of thesliding contact member and rotating contact member.
 4. The method ofclaim 3, wherein said axial member is a spring which exerts between44.48-111.20N (10-25 lbf) of force in the axial direction when therotating coupler is assembled.
 5. The method of claim 1, wherein saidrotating coupler assembly can rotate continuously and can initiaterotation about the central axis by overcoming an initial frictionalresistance to axial rotation generated by the contact surfaces of therotating contact member and sliding contact member with a breakawaytorque of ˜0.202 N-m (1.79 ft-lbs) or less.
 6. The method of claim 1,wherein said sliding contact member is able to move in the axialdirection but is mechanically prevented from rotating about the centralaxis.
 7. The method of claim 1, wherein said receiving member ismechanically prevented from rotating about the central axis or moving inthe axial direction along the central axis.
 8. The method of claim 1,wherein said sliding contact member is axially disposed within thereceiving member.
 9. The method of claim 1, wherein said at least oneradial contact member is a canted coil spring capable of conducting atleast 800 amps of current.
 10. The method of claim 1, wherein said atleast one radial contact member is compressible and capable ofconducting at least 800 amps of current.
 11. The method of claim 1,wherein the contact surfaces of the sliding contact member and rotatingcontact member are mating conical surfaces.
 12. The method of claim 1,wherein the contact surface of the sliding contact member is concave andthe contact surface of the rotating contact member is convex.
 13. Themethod claim 1 further comprising: an electrical and mechanical joint atthe proximal end of the rotating coupler assembly; wherein the rotatingcoupler assembly can be independently separated from a supply cable viaa detachable connection.
 14. The method of claim 13 further comprising:a sliding member and a receiving member which are in electrical andmechanical communication via a radial contact member; wherein the radialcontact member allows for quick and repeatable detachment and assemblybetween the supply cable and rotating coupler assembly.
 15. The methodof claim 13, wherein said electrical and mechanical joint is capable ofconducting 0-800 amps of electrical current.
 16. The method of claim 1,wherein a pneumatic seal is disposed between the rotating contact memberand sliding contact member.
 17. A method of operating a welding torchassembly using a rotating coupler assembly comprising a central axis, aconstant pressure apparatus, and a rotating contact member, the methodcomprising the steps of: creating an electrical connection between therotating contact member and the constant pressure apparatus, preventingthe constant pressure apparatus from rotating about the central axis,supporting the rotating contact member with at least one sealed bearing,rotating the rotating contact member about the central axis.
 18. Themethod of operating a welding torch of claim 17, wherein the rotatingcoupler assembly further comprises: a substantially cylindrical outerhousing with a proximal and distal end; a substantially cylindricalinner housing with a proximal and distal end axially disposed within theouter housing; wherein the at least one sealed bearing is disposedbetween the inner housing and rotating contact member; wherein thecentral axis defines a center of the rotating coupler assembly; therotating contact member is substantially cylindrical with a proximal anddistal end axially disposed within the inner housing, the constantpressure apparatus has a proximal and distal end axially disposed withinthe inner housing, and the rotating contact member is able to rotateabout the central axis of the rotating coupler assembly during operationof the electric welding torch and the proximal end of the rotatingcontact member is in mechanical and electrical communication with thedistal end of the constant pressure apparatus.
 19. The method ofoperating a welding torch of claim 18, wherein the constant pressureapparatus further comprises: a sliding contact member with a proximaland distal end; a receiving member with a proximal and distal end; ananti-rotation member in mechanical communication with the slidingcontact member and the receiving member; an axial force member inmechanical communication with the receiving member and the slidingcontact member; wherein the axial force member exerts a force in theaxial direction, along the central axis, against the receiving memberand the sliding contact member; and wherein the sliding contact memberis able to move in the axial direction, along the central axis, andmaintain electrical and mechanical communication with at least oneradial contact member which is in electrical and mechanicalcommunication with the receiving member.